Asthma do not counteract smoking initiation

Abstract

Background: The proportion of smokers among individuals with asthma is often similar, or even higher, as the general population. Whether early onset of asthma deters from smoking initiation has rarely been studied.

Aim: To study the association between age at onset of asthma and initiation of daily smoking.

Method: In a prospective study about asthma and allergic diseases within the Obstructive Lung Disease in Northern Sweden (OLIN) studies, a cohort of children (n=3430 at recruitment in 1996) participated in questionnaire surveys at ages 8y, 12y, 19y and 28y. Questions about tobacco use were included from age 12y. Asthma was defined as self-reported physician-diagnosed asthma.

Results: Physician-diagnosed asthma was reported by 18% (n=603) until age 28y, of which 49% had onset at age 12y or younger (early onset), 32% onset from 12 to 19y (teenage onset), and 19% onset from 20 to 28y (late onset). Throughout the cohort study, 20% (n=670) were daily smokers at the time of least one survey, of which 34% started smoking at age 15y or younger, 61% from 16 to 19y, and 5% from 20-28y. Ever smoking was more common in individuals with than without asthma, 25 vs 19% (p=0.021).The prevalence of ever daily smoking was 19% in non-asthma, 24% in early onset, 25% in teenage onset, and 20% in late onset asthma (p=0.097). Ever daily smoking was associated with female sex (OR 1.5 95%CI 1.3-1.8), having a smoking mother at age 8y (2.1;1.8-2.5) and early onset asthma (1.4;1.0-1.8), but not teenage or late onset asthma or family history of asthma.

Conclusion: Smoking was more common among individuals with than without asthma and importantly, having early onset of asthma did not counteract smoking initiation.